How to say "radical" in Chinese??

I was talking to my friends at the coffee shop about something and the topic of "radicals" came up.. and I had a heck of time trying to explain what I mean by "radical".. They thought I was talking about "radiance" at first because I was talking about the "fire" radical.. hehe.. then they pulled out their dictionary and looked it up and of course they found "radical" as in the sentence "He had some very radical ideas.".. as in abnormal etc..

I have now looked it up in my English-Chinese PlecoDict and got two possibilities..

bùjiàn and bùshǒu

So when I go back to see them tomorrow, I want to know which of these would be the correct word? I am thinking bùshǒu due to the translation I am seeing.. but I could be wrong.. :)